I have a Tier 1 level 20 Cavalry Plate that I plan to upgrade to Tier 2 next time Crystal Cove is run.
One of my characters hit level 20, can use this item now, and I'm thinking about adding the +1AC Stone of Change eldritch ritual on it. Might adding this to it mess up the item's ability to be upgraded during Crystal Cove? I'm uncertain how touchy the Crystal Cove upgrading might be. (My gut feeling is that perhaps it would be able to be upgraded to Tier 2 with no problems, but it would delete the Stone of Change ritual.)